A073804 Number of divisors of n is greater than that of sigma[n].

4, 9, 16, 18, 25, 36, 48, 50, 64, 72, 80, 81, 100, 112, 144, 162, 180, 192, 196, 200, 208, 225, 240, 252, 256, 288, 289, 300, 320, 324, 336, 400, 432, 441, 448, 450, 468, 484, 512, 576, 578, 592, 624, 625, 648, 676, 700, 704, 720, 729, 768, 784, 800, 810, 832

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Formula

Solutions to A000005(x)>A062068(x)=A000005[A000203(x)]

Example

x=25: D[25]={1,5,25},3 divisors; D[sigma(25)]={1,31},2 divisors; 2<3, so 25 is here. x-48:D[48]={1,2,3,4,6,8,12,16,24,48},10 divisors; D[sigma(48)]={1,2,4,31,62,124},6 divisors, 6<10 so 48 is here.

Mathematica

Do[s=DivisorSigma[0, DivisorSigma[1, n]]; s0=DivisorSigma[0, n]; If[Greater[s0, s], Print[n]], {n, 1, 1000}]
Select[Range[900], DivisorSigma[0, #]>DivisorSigma[0, DivisorSigma[1, #]]&] (* Harvey P. Dale, Jan 18 2017 *)

Crossrefs

Cf. A000005, A000203, A062068, A073802, A073803, A037197.

Sequence in context: A235993 A102646 A104021 * A219364 A195212 A332443

Adjacent sequences: A073801 A073802 A073803 * A073805 A073806 A073807

Keyword

nonn

Author

Labos Elemer, Aug 13 2002

Status

approved